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Comment by celim307 | Hacker News Reader

That’s a looooooot of salt, way more than you’re ever gonna use up through food, and it’s heavy. And corrosive.

1,000,000 humans require 4,000,000 liters of water daily. Seawater is 3.5% salt (35g/l), giving us 140,000,000g of salt. If we assume NaCl, with a density of 2.17g/cm3, that gives us 64,500,000 cm3 of salt, or 64.5 m3. I am getting a range of capacities on dump trucks, but somewhere on the order of 10m3 per truck. So 6-7 dump trucks dropping salt into the middle of nowhere. That does not sound like an infeasible problem for maintaining 1e6 humans?

Expecting Cunningham’s Law to show I goofed the math.

Humans require a lot more than 4L daily if you count sanitation, food production, and so on. But it’s still true that ultimately it’s not a lot of water if we wanted to put our minds to it.

I think your main issue is that the NaCl doesn't come out in a pure crystalline form. It's a higher concentrated brine but still contains an awful lot of water.

Nuts, that is an excellent point. I am failing to find the outflow concentration of salt, but you are correct that the output is likely to be only mildly concentrated (eg 7% salt). For all I know, it take an order of magnitude more energy to emit pure salt rather than a brine. Total amount of salt is not insurmountable, but the volume of output would be challenging quickly without enormous evaporation pools.

My understanding is some US salt flats are actually restored on annual basis to facilitate high speed racing on them. So if you didn't mind trucking it a very long distance, they'd be happy to have you dump it out there.

You have 4 liters of water per person? That's what, only drinking?

Average household water use in 100-200 liters per day.

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